Sorry it has taken me so long to put these up. I put the switch in the same general area as the instructions. It just seemed to be a good place with lots of room for error. My one "regret" is that it seems to be a little far back and is awkward to reach. It sits almost directly beside my arm when I drive so I have to pull my arm back to fumble for it if I'm not looking. Its not a bad position, just one that takes getting used to. I'm about 5'11" (179cm), so for anyone about that height or taller it should be fine, but if you're much shorter than that you may want to find a different place to put it.
http://gallery.me.com/casey_mitchiner/100031/IMG_0146/web.jpg?ver=12496733900001
I also currently have the cable just coming out of the side panel. I may move it later. I don't know yet. The cable is definitely long enough to put whatever you have it plugged into almost anywhere. It easily reaches the back seat.
http://gallery.me.com/casey_mitchiner/100031/IMG_0148/web.jpg?ver=12496734010001